Benefits of OpenBSD

I just began helping an international non-profit environmental
group(Surfrider Foundation) with 15 users users on Mac and Win machines.
They just changed offices and are looking at moving from a peer-to-peer
setup with 7 dialups and a cablemodem(why?) to a server for
file/printer/email/internet access. Their current tech guy, the same one
who got them into their current money wasting predicament, is pushing NT
or Novell 5.0 on them. Aside from the primary cost issue( $12K w/
licenses for NT) I have serious issues with Microsoft's cavelier
attitude towards security. Surfrider's needs are extremely simple and
have nothing to steal, except goodwill. But why should they pay to put
themselves at risk? Could someone please give me a few fundamental
security advantages, besides cost, of OpenBSD over NT and Novell(I have
little experience with either) that I can use to convince SF's Executive
Director not waste the money.
Also, I just read an article on the Gartner Group's new study that
show's the true cost of migrating(and everyone will have to, Microsoft
style) from NT to Win2000 is between $2,500 and $3,100 per machine.
Obviously, that is how they are going to keep the gravy train rolling
through the next decade. Here's the link if you have'nt read it yet.
Thanks, Victor
http://news.cnet.com/news/0-1003-200-114579.html